1. Field of the Invention
This invention relates to a liquid crystal display device and more particularly to a device which is capable of automatically adjusting a contrast of a liquid crystal display screen.
2. Description of the Related Art
From the viewpoints of miniaturization and power saving, a liquid crystal display (LCD) is adopted as a display in many information processors such as personal computers. Generally, the LCD is provided with a contrast control, which can be handled manually by the user to adjust the contrast of the screen as desired.
However, usually the brightness of the LCD will be dark at low temperatures and light at high temperatures, thus the user must handle the contrast control to adjust the contrast as temperature rises while the LCD is operating.
To solve such a problem, it is also possible to automatically adjust the contrast in response to a temperature. However, whether or not the contrast is optimum varies from one person to another, and if it is adjusted according to a specific adjustment rule, namely, a temperature vs. drive voltage characteristic, the contrast cannot necessarily be adjusted so that it becomes optimum for every user. LCDs vary in characteristics to some degree depending on manufacture, and differ in contrast even at the same drive voltage; they do not include means capable of solving such inconvenience.